Evolution of Cu-L-alpha fluorescence lineshape during aging of Cu-Al studied with direct excitation by undulator radiation

The high sensitivity obtained by direct excitation by undulator radiation a llows the shape of the Cu-L-alpha beta fluorescence spectrum to be measured accurately also at low Cu concentrations. We study the evolution of the L- alpha lineshape of 0.5 and 1.5% Cu in Al following the thermal history of t he sample. The Cu spectra in the precipitates are given and the formation o f Guinier-Preston (GP1) zone of type 1 is studied for the first time with t his approach. The results point out the importance of GPI arrangement with platelets rich in Cu. The effect of selfabsorption on the L-alpha beta spec tra is also investigated. (C) 1999 Elsevier Science B.V. All rights reserve d.